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Pathogenic Viruses

Pathogenic Viruses. Name of virus what family it belongs to what disease it causes, organ system affected DNA or RNA? Route of transmission; reservoirs, vectors Viral virulence factors (selected viruses) Immunizations. Herpes virus family. Herpes family of DNA viruses

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Pathogenic Viruses

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  1. Pathogenic Viruses • Name of virus • what family it belongs to • what disease it causes, organ system affected • DNA or RNA? • Route of transmission; reservoirs, vectors • Viral virulence factors (selected viruses) • Immunizations

  2. Herpes virus family • Herpes family of DNA viruses • As a family, infects epithelial cells, lymph cells, and/or nerve cells. • Associated with latent infections and cancer • Spread by direct contact, fluid exchange • Herpes simplex 1 (cold sores) and 2 (STD) • Drug treatment: acyclovir and related drugs • Cannot be cured

  3. Herpes continued • Varicella zoster: chickenpox; reactivation of latent state: shingles • Varivax vaccine protects • Drugs limit severity, duration of shingles • Epstein Bar virus: mononucleosis • Infection of B cells and salivary glands • Sore throat, fatigue, brittle spleen • Cytomegalovirus: CMV • Common, subclinical infection • Severe problem with AIDS, transplants, and cause of birth defects

  4. Common cold viruses • Rhinovirus (picornavirus, small RNA virus) • Most common • Coronavirus (RNA virus) • Related to virus that causes SARS • Sudden acute respiratory distress syndrome • Adenovirus (DNA virus) • Some strains cause GI distress instead • Parainfluenza virus (RNA) • Related to flu and measles Spread by various forms of contact.

  5. Parainfluenza family (RNA) • Rubeola (measles) • Highly contagious, possible serious complications • Systemic infection, red rash • US: immunized with MMR vaccine; under control • Mumps virus • Infects parotid glands, many other glands • Deafness most serious complication • US: immunized with MMR vaccine; under control • Parainfluenza virus • Mild respiratory infection, cold symptoms

  6. Parainfluenza family continued • Respiratory syncytial virus (RSV) • Host: young children, can be fatal in infants • Cold symptoms in older individuals • Virus spreads in host by forming syncytia • NOT a parainfluenza virus but similar spread and symptoms: German Measles (Rubeola) • Due to birth defects, women of child-bearing age should have immunity. • US: immunized with MMR vaccine; under control

  7. Viruses of the GI tract • All RNA viruses (either ss or ds) • Enterovirus • Picornavirus family, includes polio, Hepatitis A • Norovirus • Rotavirus Spread by fecal-oral route of transmission; cause of outbreaks in daycares, restaurants, cruise ships, etc. vomiting and diarrhea.

  8. Animal associated viruses • Rhabdovirus: cause of rabies • Infects brain and salivary glands • Animals spread virus in saliva by biting • Slow acting, can be immunized against after • Nearly always fatal unless treated. • Arboviruses • Unrelated viruses spread primarily by mosquitoes • Affect other creatures (horses, birds) as well as humans • Locally important ones cause encephalitis

  9. continued • St. Louis encephalitis • Eastern Equine encephalitis • Kills people and horses • West Nile virus • Generally mild in people, but kills certain birds Other arboviruses (e.g. Dengue fever) more of a tropical problem, but if global warming continues, becomes OUR problem. Endemic in Mexico.

  10. Fungi • Systemic infections • Generally acquired by inhalation of spores • Lung infections, may spread beyond into other tissues • Histoplasma (histoplasmosis) • Most common in this area (Ohio and Miss. River valleys) • Soil contaminated with bird or bat droppings • Many people exposed with asymptomatic cases

  11. Opportunists • Aspergillus (aspergillosis) • Variety of species, very common in soil, plant materials • Serious infections in immunocompromised • Poisoning from aflatoxin from A. flavus • Cryptococcus neoformans • Inhalation of spores, has predilection for CNS • Particularly serious in AIDS • Pneumocystis carinii • Very protozoan like, but is a fungus • Most cases associated with AIDS • Serious lung infections: PCP (P. carinii pneumonia)

  12. Protozoans • Eukaryotic single-celled organisms • Eukaryotic means harder to treat infections • Group responsible for human diseases are the animal-like protozoa. • Protozoa are widespread in nature, most not pathogenic • Protozoa typically have life cycles • Simple, like vegetative cell and cyst (spore-like): Amoebas • Complex, like sporozoans have

  13. Protozoal diarrheas • Cryptosporidium • Primarily livestock and poultry, acquired fecal-oral through food or contaminated water. • Diarrhea, but systemic spread as well, highly dangerous to AIDS patients. • Giardia lamblia: • Hiker’s diarrhea, from many water sources • Common cause of diarrhea; 1-4 weeks.

  14. Other problem protozoal diseases • Trypanosoma: various species, geographic locations • Cause of African sleeping sickness, spread by bite of tsetse fly: Infection of CNS, causes coma • Cause of Chagas disease, spread by bite of reduviid bug: eventually damages heart tissue. • Leishmania: • Causes leishmaniasis, spread by sandfly (see “Gulf war”) • Various levels of severity of systemic disease • Toxoplasma: toxoplasmosis • kills fetus; many organs in immune compromised . • Part of life cycle involves cats, so pregnant women must stay away from litter box.

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